Isolating connector

ABSTRACT

A connector for interconnecting or mutually isolating two circuits one of which is connected to a first connector element ( 1 ) and the other of which is connected to a second connector element ( 2 ) which is interengageable with the first. One of the connector elements supports a first contact ( 12 ) connected to a respective circuit and a displaceable contact holder ( 4 ) carrying interconnected second ( 14 ) and third ( 15 ) contacts. The contact holder is displaceable between a first position in which the first ( 12 ) and second ( 14 ) contacts are separated and a second position in which the first and second contacts are interconnected. The connector elements are formed such that on interengagement the contact holder is displaced from the first to the second position after the third contact is interconnected with a contact ( 34 ) of the other connector element ( 2 ). The arrangement is such that on disengagement of the connector elements ( 1, 2 ) the contact holder is displaced from the second to the first position. The contacts are arranged such that on disengagement the first and second contacts separate before the third contact is separated from the other connector element and such that when separated the first and second contacts are located within a closed chamber defined within the connector element in which the contact holder is supported.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to: PCT Application No. PCT/GB00/00312filed on Feb. 4, 2000; and Great Britain Application No. 9902467.1 filedon Feb. 5, 1999.

BACKGROUND OF THE INVENTION

The present invention relates to an isolating connector forinterconnecting or mutually isolating two or more circuits.

Electrical connectors are required which can be used safely inapplications where the connectors may be exposed to explosiveatmospheres. Such applications are found in industrial plants, forexample in the oil, gas, petrochemical and mining industries.

Industrial plants are zoned according to the likelihood of explosivegases being present. Various protection measures are used to preventexplosions. The International Electromechanical Commission (OEC) hasestablished standards which should be applied in particularcircumstances, for example the Exd standard. Connectors in accordancewith the Exd standard should be capable of being used in an explosiveatmosphere such that if two interengageable connector elements of theconnector are separated and a spark is generated any resultant explosionoccurs within the connector structure and is prevented from beingtransmitted to the surrounding environment. To meet these standards, theconnector must be capable of withstanding pressure developed within theconnector as a result of an internal explosion and preventing thetransmission of the explosion along any flame path defined betweencomponents of the connector. Exd standard connectors are available atpresent but generally meet the standard requirements only if prior todisconnection of the connector elements no power is supplied to theconnector elements. To prevent accidental disconnection when power isstill being supplied to the connector, such connectors must be markedclearly with for example “do not separate when energised” and theconnector elements must be secured together by means of specialfasteners which prevent accidental release.

It is an object of the present invention to provide a connector whichcan meet stringent safety requirements even if elements of the connectorare separated when still connected to a source of electrical energy.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a connector forinterconnecting or mutually isolating two or more circuits, comprisingfirst and second interengageable connector elements each of which isconnected in use to a respective circuit and at least one of whichsupports a first contact connected to the respective circuit and adisplaceable contact holder carrying interconnected second and thirdcontacts, the contact holder being displaceable between a first positionin which the first and second contacts are separated and a secondposition in which the first and second contacts are interconnected,wherein the connector elements are formed such that on interengagementthe contact holder is displaced from the first to the second positionafter the third contact is interconnected with a contact of the otherconnector element, and such that on disengagement the contact holder isdisplaced from the second to the first position, the contacts beingimaged such that on disengagement the first and second contacts separatebefore the third contact is separated from the said contact of the otherconnector element and such that when separated the first and secondcontacts are located within a closed chamber defined within the said atleast one connector element, means being provided for locking the oreach contact holder 10 the said contact of the other connector elementunless the first and second contacts are separated.

Each connector element may support a respective first contact and arespective displaceable contact holder carrying interconnected secondand third contacts such that on interengagement of the connectorelements the third contacts are interconnected. Means may be provided toprevent the or each contact holder being blown out of the associatedconnector element. The preventing means may comprise a pin received in aslot formed in the contact holder.

The or each contact holder is preferably slidable in a bore such thatthe closed chamber is defined between the contact holder and the wallsof that bore. Preferably, the locking means provided for locking the oreach contact holder to the said contact of the other connector elementcomprise one or more locking balls which are retained in lockingengagement between the connector elements and the contact holder unlessthe contact holder is in the first position.

Means may be provided for locking the or each contact holder in thefirst position when the connector elements are separated. Preferably thelocking means maintains the or each contact holder in the first positionunless the contact elements are interengaged, and may comprise aspring-biased slider displaceable as a result of interengagement of theconnector elements from one position in which it reins one or morelocking balls in locking engagement between the connector element andthe contact holder with the contact holder in the first position and afurther position in which each locking ball is released and the contactholder is displaceable to the second position.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will now be described, by way ofexample, with reference to the accompanying drawings, in which;

FIG. 1 is an outside view of the two connector elements making up aconnector in accordance with one embodiment of the present invention;

FIG. 2 is a sectional view through the connector assembly of FIG. 1;

FIGS. 3 to 9 illustrate successive stages in the interconnection of theconnector element shown in FIGS. 1 and 2; and

FIGS. 10 to 15 illustrate the sequence of component movements which isfollowed as the two connector elements are separated.

DETAILED DESCRIPTION

Referring to FIG. 1, the illustrated connector assembly comprises a maleconnector having an outer body 1 and a female connector having an outerbody 2. A collar 3 is slidably supported on the female connector outerbody 2. The tip of a male body sliding contact holder 4 is also visible.

Referring to FIG. 2, this view corresponds to that of FIG. 1 but shownin axial section to reveal the internal structure of the male and femaleconnectors. The male connector outer body 1 fixedly supports a maleconnector inner body 5, an annular recess being defined between theinner and outer bodies. A male connector slider 6 is slidably receivedwithin the recess between the inner body 5 and the outer body 1 and aseries of compression springs 7 biases the slider 6 against a flange 8supported by the inner body 5. The inner body 5 defines a socket 9 inwhich a male connector fixed contact holder 10 is received. Cable solderpots 11 extend into the socket 9, and the holder 10 supports first malecontact pins 12 which project into a further socket 13 defined by theinner body 5.

The pins 12 face first female contacts 14 supported in the slidingcontact holder 4. The sliding contact holder 4 also supports secondfemale contacts 15 which are electrically connected to the first femalecontacts 14. The holder 4 is slidable within the socket 13 but isretained in the position shown in FIG. 2 by a lock ball 16. The maximumspacing between the pins 12 and the first female contacts 14 isdetermined by the position of a retention pin 17 that is received withina slot 18 formed on the outer surface of the holder 4. The pin 17 isfixedly mounted in the male connector inner body 5, providing radialorientation and preventing total withdrawal of the sliding contactholder 4 from the inner body 5.

The female connector outer body 2 fixedly supports a female connectorinner body 19. An annular slot is defined between the outer body 2 andthe inner body 19 and receives a female connector slider 20 which isbiased by a compression spring 21 against a frusto conical surface 22defined by the inner body 19. A compression spring 23 biases the collar3 against a retaining circlip 24. A lock ball 25 is supported in atapering opening in the female connector outer body 2. An O-ring seal 26is also provided in an annular groove inside the open end of the femaleconnector outer body 2.

The female connector inner body 19 defines a socket 27 which receives afemale connector fixed contact holder 28. The inner body 19 also definesa socket 29 which slidably receives a female connector sliding contactholder 30. In the separated condition of the connector assembly thesliding contact holder 30 is locked in position by a lock ball 31. Thesliding contact holder 30 defines a socket 32 the wall of which carrieslock balls 33 and into which second male contact pins 34 project. Thepins 34 are connected to third female contacts 35 also carried by thesliding contact holder 30. The third female contacts 35 face third malecontact pins 36 ex-ending from the fixed contact holder 28. The thirdmale contact pins 36 are connected to cable solder pots 37 which projectinto the socket 27.

The maximum spacing between the third female contacts 35 and the thirdmale contact pins 36 is determined by retention pin 38 carried by theinner body 19. The retention pin 38 is received in an elongate slot 39formed in the outer surface of the female connector sliding contactholder 30. The pin 38 provides radial orientation and prevents totalwithdrawal of the contact holder 30 from the inner body 19.

Referring now to FIGS. 3 to 9, the interaction of the various componentsdescribed with reference to FIG. 2 as the male and female connectors arebrought together will be described. As the tip of the male connectorouter body 1 is advanced into the female connector body 2 the lock balls33 are pushed radially outwards and the O-ring seal 26 is compressed.The tip of the male connector outer body 1 then contacts one end of thefemale connector slider 20. As the male connector is advanced furtherinto the female connector the slider 20 is pushed back against thecompression spring 21. Initially the lock ball 31 secures the slidingcontact holder 30 against axial displacement and as a result the maleconnector sliding contact holder 4 which in turn is locked against axialdisplacement by lock ball 16 advances so as to push the second femalecontacts 15 onto the second male contact pins 34. Once the femaleconnector slider 20 has moved far enough against the biasing force ofthe spring 21 the lock ball 31 can move away from the female connectorsliding contact holder 30 so as to enable axial displacement of thecontact holder 30. FIG. 4 shows the assembly just after the lock ball 31has released the holder 30 for axial displacement.

Referring to FIG. 5, as the male connector is pushed further into thefemale connector, the slider 20 is pushed back further against thebiasing force of the spring 21 and the contact holder 30 advancestowards the third male contact pins 36. As a result the retention pin 38is no longer at one end of the slot 39.

As shown in FIG. 6, further advancement of the male connector pushes thethird female contacts 35 onto the third male contacts 36. Te lock ball16 still prevents axial displacement of the male connector slidingcontact holder 4.

FIG. 7 shows the relative positions of the various componentsimmediately after the female connector sliding contact holder 30 hasbeen pushed up against the bottom of the socket 29 defined by the innerbody 19 of the female connector. It will be seen that the tip 40 of theinner body 19 has pushed the male connector slider 6 back against thebiasing force of the spring 7 to a sufficient extent that the lock ball16 can move out of engagement with the male connector sliding contactholder 4. Further advancement of the male corrector outer body 1 intothe female connector causes further compression of the spring 7 as shownin FIG. 8 until the first male contact pins 12 enter the first femalecontacts 14. The male connector is then pushed fully home to theposition shown in FIG. 9, in which position the lock balls 25 are pushedinto an annular depression formed in the outer body 1 of the maleconnector, the lock balls 25 being retained in position by the collar 3which is pushed over the lock balls 25 by the spring 23. Thus the cablesolder pots 11 are directly connected to the cable solder pots 37through a series of three connections each defined by male contact pinsreceived in female contacts.

Referring now to FIGS. 10 to 15, the sequence of component movementwhich is followed as the male and female connectors are separated willbe described. Firstly, as shown in FIG. 10, the collar 3 is pulled backto release the lock balls 25. Tension is then applied between the collar3 and the outer body 1 of the male connector so as to pull the twohalves of The connector apart. The lock balls 33 prevent separation ofthe male connector sliding contact holder 4 and the female connectorsliding contact holder 30. Thus the tension is applied to theconnections between the first male pins 12 and female contacts 14 andthe third male pins 36 and the female contacts 35. Depending upon whichof these two pin and female contact connections presents the greatestfrictional resistance to separation, either the pins 36 will be pulledout of the female contacts 35 as shown in FIG. 10 or the pins 12 will bepulled out of the female contacts 14 as shown in FIG. 11 (FIG. 11 showsonly the internal components of the connector). Further separation ofthe male and female connector parts moves the assembly to the positionas shown in FIG. 12 (if initial separation was between pins 36 andfemale contacts 35 as shown in FIG. 10) or moves the components of theassembly to the relative positions shown in FIG. 13 (if initialseparation was between the pins 12 and the female contacts 14 as shownin FIG. 11). Thus the two contact holders which are locked together havebeen separated from either the male connector fixed contact holder 10 orthe female connector fixed contact holder 28.

The male and female connector sliding contact holders remain lockedtogether and thus as the male and female connectors are pulled fartherapart the assembly components assume the condition shown in FIG. 14 inwhich the locked-together sliding contact holders are electricallyisolated from the first male connector pins 12 and the third maleconnector pins 36. As the male and female connector parts are pulledfurther apart to the positions shown in FIG. 14 the lock balls 33 arereleased and as a result the two sliding contact holders 4 and 30 canseparate as shown in FIG. 15. As a result the second male contact pins34 are pulled out of the second female contacts 15. All three sets ofmale pins and female contacts are thus separated and further separationof the two halves of the connector can then proceed.

Assuming that when making or breaking a connection with the illustratedconnector power is applied between the cable solder ports 11 and 37,connection or disconnection of the connector assembly will neverthelessbe achieved in a safe manner. For example, if as shown in FIG. 12 theelectrical circuit is broken first as a result of separation of the malepins 36 and the female contacts 35, any resultant spark will begenerated in the closed compartment defined around the pins 36. Even ifthat compartment is filled with an explosive mixture of gas which isignited as a result of spark generation, the volume of gas ignited willbe relatively small. A gas explosion in the closed compartment willresult in an axial force being applied to the female connector slidingcontact holder 30 but that contact holder will be prevented from beingblown out of the assembly as a result of interengagement between theretaining pin 38 and the slot 39. Heat generated by the confinedexplosion will be rapidly absorbed by the connector body, and the lengthof any leakage path from the closed compartment in which the explosionhas occurred to the exterior of the connector will be such that theexplosion cannot be propagated to the atmosphere outside the connector.Similarly, if the first break in the electrical connection through theconnector assembly is a result of the pins 12 being pulled out of thefemale contacts 14 as shown in FIG. 13, any spark will be generated inthe closed compartment defined around the pins 12 and the male connectorsliding contact holder 4 will be retained within the connector body byinteraction between the retaining pins 17 and the slot 18. Furtherseparation of the device will result in the separation of two furthersets of male pins and female contacts but no voltage will be appliedacross those connections at the lime of separation and accordingly nofurther sparks can be generated. The overall assembly is thus inherentlysecure against the risk of sparks being generated in a manner whichcould cause explosions to propagate outside the connector body.

Once the connector has been disconnected the two halves of the connectorare in the condition as illustrated in FIG. 2. In that condition, themale connector sliding contact holder 4 is locked against axialdisplacement by the lock ball 16 and the female connector slidingcontact holder 30 is locked against axial displacement by the lock ball31. Thus even if a user was to inadvertently apply an axial force to oneof the contact holders the contact holder would not be displaced axiallyand therefore could not make an electrical connection with any cableconnected to the respective connector half. The overall assembly is thusinherently very secure against threats either to the safety of users orto the generation of explosions which could propagate to the surroundingenvironment.

It will be appreciated that alternative arrangements to those describedin FIGS. 1 to 15 can be envisaged. For example sprung contactarrangements could be used in place of the illustrated pins and sockets.Spring loaded arrangements could be provided to apply a bias force toassist separation of particular pins and sockets in a predeterminedorder. A captive screw thread ring nut or staplelock system could beused to hold the collar 3 in a locked position so as to reduce the riskof inadvertent connector separation. The sliding collars 6 and 20 couldbe multi-component assemblies. Furthermore, although in the illustratedconnector only straightforward electrical connections are required, theconnector could be used for combined electrical/fibre optic connectionor for a fibre optic connection only. Combined connectors could alsoinclude pneumatic and/or hydraulic connections.

Further modifications to the illustrated connector arrangement arepossible. For example, the springs of the illustrated embodiment couldbe replaced by foam rubber, compressable gas arrangements or a singlelarge spring. The annular collars could be replaced by sliding rods orthe like. Locking balls could be replaced by shaped pin or other lockingelements. The retention posts could be replaced by anchor bolts,circlips, machine leas or lips or the like. Collars could be split intoa series of independent elements to improve security against tampering.In the illustrated arrangement, the retention posts slide in axial slotswhich limit the maximum axial displacement of the contact holders. Otherarrangements are possible however. For example a spring-loaded retentionpost could be slidable in a slot incorporating a first axially extendingslot section and a second slot section which is inclined at an acuteangle to the axial section. With such an arrangement if when the contactelements were disconnected an attempt was made to push back the contactholder, the springloaded retention post could cause the pin holder torotate into a locked position, thereby preventing reconnection of thepins. With such an arrangement, the springloading, would cause rotationof the contact holder unless the contact holder was prevented fromturning as a result of inierengagement with components of the otherconnector elements. For example, pins mounted on one contact elementwould engage in sockets of the contact holder of the other contactelements so as to prevent rotation of the contact holder. Such anarrangement would not positively lock the contact holders against axialdisplacement before connector element interengagement as is the case forthe illustrated embodiment.

It will be appreciated that connectors in accordance with the inventionmay be provided with air or inert gas purging, to prevent the build-upof explosive gas mixtures in the closed chambers in which sparks may begenerated, or the closed chambers may be filled with a non-flammableelectrically insulating liquid.

1. A connector for interconnecting or mutually isolating two or morecircuits, comprising first and second interengageable connector elementseach of which is connected in use to a respective circuit and at leastone of which supports a first contact connected to the respectivecircuit and a displaceable contact holder carrying interconnected secondand third contacts, the contact holder being displaceable between afirst position in which the first and second contacts are separated anda second position in which the first and second contacts areinterconnected, wherein the connector elements comprise means forensuring that on interengagement the contact bolder is not displacedfrom the first to the second position unless the third contact isinterconnected with a contact of the other connector element, theconnector elements comprise means for ensuring that on disengagement thecontact holder is displaced from the second to the first position, andthe connector elements comprise means for ensuring that on disengagementthe first and second contacts separate before the third contact isseparated from the said contact of the other connector element and suchthat when separated the first and second contacts are located within aclosed chamber defined within the said at least one connector element,means being provided for locking the third contact of the contact holderto the said contact of the other connector element unless the first andsecond contacts are separated.
 2. A connector according to claim 1,wherein the contact holder is slidable in a bore such that the closedchamber is defined between the contact holder and walls of the bore. 3.A connector according to claim 1, wherein the means for locking thecontact holder to the said contact of the other connector elementscomprise one or more locking balls which are retained in lockingengagement between the connector element and the contact holder unlessthe contact holder is in the first position.
 4. A connector according toclaim 1, wherein means are provided to prevent the contact holder frombeing blown oat of the associated connector element.
 5. A connectoraccording to claim 4, wherein the preventing means comprises a pinreceived in a slot formed in the contact holder.
 6. A connectoraccording to claim 1, wherein each connector element supports arespective first contact and a respective displaceable contact holdercarrying interconnected second and third contacts such that oninterengagement of the connector elements the third contacts areinterconnected.
 7. A connector according to claim 6, wherein means areprovided to prevent each contact holder from being blown out of theassociated connector element.
 8. A connector according to claim 7,wherein the preventing means comprises a pin received in a slot formedin the contact holder.
 9. A connector according to claim 1, comprisingmeans for locking the contact holder in the first position when theconnector elements are separated.
 10. A connector according to claim 9,wherein the locking means locks the contact holder in the first positionunless the third contact is interconnected with the contact of the otherconnector element.
 11. A connector according to claim 9, wherein thelocking means maintain the contact bolder in the first position unlessthe connector elements are interengaged.
 12. A connector according toclaim 11, wherein the locking means comprise a spring-biased sliderdisplaceable as a result of interengagement of the connector elementsfrom one position in which it retains one or more locking balls inlocking engagement between the connector element and the contact bolderwith the contact holder in the first position and a further position inwhich the locking, ball is released and the contact holder isdisplaceable to the second position.